Take a moment to consider a system in which an inverter unit (i.e., power electronics device) that converts the power is provided with a communication function and autonomous cooperative control such as power source phasing and power allocation is applied between a plurality of power electronics devices to maintain the flexibility of operations while automatically implementing a capacity change even at the time of expansion and the time when an abnormality occurs.
In such a system, it is considered that a plurality of power electronics devices mount a function called “power allocation control” to dynamically distribute the power input/output within the electrical power handling capability. Moreover, it is considered to mount a function called “output power phase synchronization control” in an application to drive the power electronics devices in parallel to increase the output of power.
The output power phase synchronization control function is to prevent an occurrence of cross current (e.g. reactive current caused by a difference of electromotive force, synchronization cross current caused by a phase difference of electromotive force and harmonic cross current caused by a waveform difference of electromotive force) in an output on the alternating-current side. In this case, it is useful for the throughput increase in the power input/output to determine the subject of control between the power electronics devices, that is, to determine a master (i.e. device of a control subject) and a slave (i.e., device of a controlled subject) and give an instruction of power information and synchronization information (e.g., time synchronization information and frequency information) from the master to the slave for power source phasing. In a case where three or more power electronics devices are connected to the same power line, since it is difficult only with information on the power line to recognize individual actual values with respect to the planned values of respective devices, power information is exchanged using the communication control and the master synchronizes with the slave.
In the related art, there is disclosed a method that a plurality of inverters in which the master/slave roles are set in a fixed manner realize parallel operation corresponding to the phase synchronization of output power by the use of synchronization by an optical communication line. Moreover, there is disclosed a method of dynamically setting software of a server that monitors and controls a device by notifying device information to the server by the use of communication when the device is connected to a system.
In a case where the master/slave roles are dynamically decided between the power electronics devices, since each device individually operates at the time of initial installation or anomalous occurrence, if the correspondence of information on a logical configuration to control power (allocation control or phase control) between the devices is not considered, there may occur a state in which operation starts in a case where a plurality of masters exist in a system. In this case, since it is difficult to unify the determination as to from which power electronics device the synchronization information is to be received for operation, there is a problem that the function of phase synchronization of output power does not operate correctly. Moreover, if an actual installation state is not considered in the decision of the sending subject of the synchronization information for the phase synchronization of output power, there is a problem that it is not possible to realize the phase synchronization at high accuracy. Such problems cannot be solved in the related art.
As described above, the roles between power electronics devices are defined in a fixed manner in the related art, and there is not disclosed a method of dynamically performing logical configuration management and role decision of power allocation control and output power phase synchronization control at the time of initial device installation or anomalous occurrence after the start of operation, and increasing the throughput of power input/output while securing the flexibility of operation. Especially, at the time of cooperative operation of a plurality of power electronics devices, the role decision taking into account an actually installed system configuration is necessary.